Two major urinary metabolities of 3-chloro-2-methylpropene (DMVC) were isolated and identified. They were 2-amino-4-thia-5-heptene-1,7 dioic acid and the corresponding N-acetylated derivative. These compounds appear to arise from oxidation of one of the methyl groups to a carboxylic acid followed by GSH conjugation and subsequent metabolism of the GSH moiety. The absorption and metabolism of 5-(4-nitrophenyl)-2,4-pentadienal (NPPO, Spydust) was investigated. The compound was readily absorbed by the gastrointestinal tract and rapidly metabolized and excreted. NPPD was not readily absorbed through the skin. A total of five metabolites were identified in urine, 4-nitocinnamic acid, 4-acetamidobenzoic acid, 4-nitro-benzoic acid, 4-nitrohippuric acid and 4-acetamidocinnamic acid. These metabolites result from some combination of oxidative metabolism of the pentadienal side chain, reduction of the nitro group, and conjugation of the resulting carboxylic acid group with glycine or amino group with acetate.